Comparative study of the in vitro inflammatory activity of three nickel salts on keratinocytes

Effects of Exercise and Dietary Modifications on Hidradenitis Suppurativa: A Systematic Review

BACKGROUND

Hidradenitis suppurativa affects up to 4% of the population worldwide. Many treatment options exist but these come with a significant side-effect profile. Exercise, weight loss, and dietary modifications may be simple inexpensive alternatives and/or adjuncts to treating this disease.

OBJECTIVES

We aimed to summarize published evidence on the effects of dietary, weight loss, and exercise interventions on the clinical course, severity, or subjective improvement of hidradenitis suppurativa and to provide a framework regarding dietary changes and exercise modalities for clinicians treating this disease.

METHODS

A literature search of Scopus (1993 onwards), PubMed (1986 onwards), and MEDLINE (OVID interface, 1946 onwards) was conducted on 22 October, 2022. Case-control studies, cohort studies, and randomized controlled trials with five or more subjects conducted on adult participants (aged >18 years) were included; case reports, case series, and review papers were excluded.

RESULTS

Fifteen studies involving 2829 patients were included, encompassing nine cohort studies, five cross-sectional studies, and one cross-over study. Patients who were female, lost more than 50 pounds (22.7 kg), or were obese prior to weight loss saw improvement in hidradenitis suppurativa severity with weight loss. There was evidence for beneficial effects of diets, such as the Mediterranean diet that minimizes sugar, highly processed carbohydrates, and dairy, and emphasizes chicken, fruits, and vegetables, in patients with hidradenitis suppurativa. Evidence also supported benefit from oral zinc and vitamin D supplementation.

CONCLUSIONS

More evidence is needed in the form of randomized controlled trials or well-designed controlled trials to evaluate the effect of exercise and dietary manipulation on the hidradenitis suppurativa disease course. Overall, there is significant but weak evidence to support improvement in hidradenitis suppurativa severity with weight loss, dietary changes, and micronutrient supplementation. There is no significant evidence to support improvement in hidradenitis suppurativa symptomology with any type of exercise intervention.

CLINICAL TRIAL REGISTRATION

This protocol was registered with PROSPERO with the registration number CRD4202235099.

Ni2+-Assisted Hydrolysis May Affect the Human Proteome; Filaggrin Degradation Ex Vivo as an Example of Possible Consequences

Deficiency in a principal epidermal barrier protein, filaggrin (FLG), is associated with multiple allergic manifestations, including atopic dermatitis and contact allergy to nickel. Toxicity caused by dermal and respiratory exposures of the general population to nickel-containing objects and particles is a deleterious side effect of modern technologies. Its molecular mechanism may include the peptide bond hydrolysis in X₁-S/T-c/p-H-c-X₂ motifs by released Ni²⁺ ions. The goal of the study was to analyse the distribution of such cleavable motifs in the human proteome and examine FLG vulnerability of nickel hydrolysis. We performed a general bioinformatic study followed by biochemical and biological analysis of a single case, the FLG protein. FLG model peptides, the recombinant monomer domain human keratinocytes in vitro and human epidermis ex vivo were used. We also investigated if the products of filaggrin Ni²⁺-hydrolysis affect the activation profile of Langerhans cells. We found X₁-S/T-c/p-H-c-X₂ motifs in 40% of human proteins, with the highest abundance in those involved in the epidermal barrier function, including FLG. We confirmed the hydrolytic vulnerability and pH-dependent Ni²⁺-assisted cleavage of FLG-derived peptides and FLG monomer, using in vitro cell culture and ex-vivo epidermal sheets; the hydrolysis contributed to the pronounced reduction in FLG in all of the models studied. We also postulated that Ni-hydrolysis might dysregulate important immune responses. Ni²⁺-assisted cleavage of barrier proteins, including FLG, may contribute to clinical disease associated with nickel exposure.

Disruptive chemicals, senescence and immortality

Carcinogenesis is thought to be a multistep process, with clonal evolution playing a central role in the process. Clonal evolution involves the repeated 'selection and succession' of rare variant cells that acquire a growth advantage over the remaining cell population through the acquisition of 'driver mutations' enabling a selective advantage in a particular micro-environment. Clonal selection is the driving force behind tumorigenesis and possesses three basic requirements: (i) effective competitive proliferation of the variant clone when compared with its neighboring cells, (ii) acquisition of an indefinite capacity for self-renewal, and (iii) establishment of sufficiently high levels of genetic and epigenetic variability to permit the emergence of rare variants. However, several questions regarding the process of clonal evolution remain. Which cellular processes initiate carcinogenesis in the first place? To what extent are environmental carcinogens responsible for the initiation of clonal evolution? What are the roles of genotoxic and non-genotoxic carcinogens in carcinogenesis? What are the underlying mechanisms responsible for chemical carcinogen-induced cellular immortality? Here, we explore the possible mechanisms of cellular immortalization, the contribution of immortalization to tumorigenesis and the mechanisms by which chemical carcinogens may contribute to these processes.

Dual effect of nickel on L-arginine/nitric oxide system in RAW 264.7 macrophages

The immunogenic mechanisms of the potent contact allergen nickel are not completely clear. Nitric oxide (NO) serves as a fundamental signalling and effector molecule in the immune system, but little is known about its possible role in immune reactions elicited by nickel. We investigated the effects of nickel on the L-arginine/inducible NO synthase (iNOS) system in a murine macrophage cell line, RAW 264.7. Both LPS-stimulated and non-stimulated RAW 264.7 cells were incubated in the presence of 0-100 μM nickel sulphate for 24 h. Subsequently, NO production, iNOS protein expression, L-arginine uptake and gene expression of iNOS and cationic amino acid transporter systems (CAT) were measured. We found that 100 μM NiSO4 increased LPS-induced nitrite production as well as the formation of [(3)H]-L-citrulline from [(3)H]-L-arginine in the RAW 264.7 cells. Correspondingly, the expression of iNOS gene and protein was also remarkably enhanced. Nevertheless, nickel had an inhibitory effect on L-arginine transport which disappeared gradually upon LPS-stimulation in parallel with an increase in NO output. LPS was found to significantly amplify CAT-3 as well as CAT-2 mRNA expression, mirroring the increase in L-arginine transport. In the range of 1-10 μM, NiSO4 did not have any additional effect on CAT mRNA expression, but at 100 μM it was able to enhance CAT-1 and CAT-3 mRNA expression upon LPS stimulation. Our data indicate that nickel interferes with macrophages' L-arginine/NOS system on multiple levels. Considering the potent biological effects of NO, these influences may contribute to nickel toxicity.

Cutaneous induction of corticotropin releasing hormone by Propionibacterium acnes extracts

The skin commensal bacillus Propionibacterium acnes is known to play a major role in the development of acne vulgaris and it is established that this bacteria is involved both in the induction and maintenance of the inflammatory phase of acne. The corticotropin releasing hormone (CRH), a neuropeptide originally isolated from the hypothalamus, is also produced by the skin. CRH has been reported to play a role in the inflammation, the production of sebum and finally the differentiation of keratinocytes. At the therapeutic level, zinc is known to act specifically on inflammatory lesions with still partially known mechanisms and thus could play an important role in the development of inflammatory acne lesions. Our objective was to study the modulation of CRH expression by keratinocytes induced by P. acnes extracts. CRH expression was examined using immunohistochemistry technique on deep-frozen sections of normal human skin explants incubated with two different extracts of P. acnes and with or without zinc salts. We observed that the membrane fraction (FM) of P. acnes increased the CRH expression in the epidermis. This result indicates that P. acnes, by stimulating the production of CRH, can both modulate the differentiation of keratinocytes and increase the local inflammation, arguing that this bacterium plays a role not only in the development of inflammatory acne lesions but also in the formation of the microcomedo in the early stages of acne.

Emerging drugs for acne

Acne vulgaris is a common skin disorder that affects most individuals at some point in their lives. It may result in significant morbidity, including cutaneous scarring and psychological impairment. Current treatments include topical retinoids, benzoyl peroxide, topical and systemic antibiotics, and systemic isotretinoin. There are growing concerns of rising antibiotic resistance, significant side effects of isotretinoin therapy, and lack of safe and effective treatment for pregnant females. Recent advances in the pathogenesis of acne have led to a greater understanding of the underlying inflammatory mechanisms and the role the Propionibacterium acnes and biofilms. This has led to the development of new therapeutic targets. This article reviews emerging treatments of acne, including topical picolinic acid, topical antibiotic dapsone, systemic zinc salts, oral antibiotic lymecycline, new formulations of and synergistic combinations of benzoyl peroxide, photodynamic therapy with topical photosensitizers and potential acne vaccines.

The effects of nickel and chromium on human keratinocytes: Differences in viability, cell associated metal and IL-1α release

This study was carried out to assess the effects of chromium and nickel upon isolated keratinocytes as an in vitro model of human skin. Keratinocytes were isolated from healthy volunteer skin samples of unknown metal sensitivity (n=10) and were compared with cells from patient biopsies of known metal sensitivity (n=7). Cells were dosed with a concentration range of nickel and chromium (0-10,000 microM) and cellular mitochondrial activity, viability, metal uptake and cytokine release were measured. Responses of primary versus passaged keratinocytes were also compared. Toxicity data from primary and passaged keratinocytes was statistically analysed by the non-linear Hill Plot model. Results showed that hexavalent chromium was significantly more cytotoxic, associated more with keratinocytes and induced a dose dependant release of IL-1alpha compared to nickel. Significant differences were observed between primary and passaged keratinocytes with regard to the toxicity of chromium and nickel and variation of response. No differences were observed in the cytotoxicity or cytokine release induced by chromium or nickel for the known sensitised biopsy patient samples (n=4) compared to patch test negative controls (n=3). The results from this study suggest human keratinocytes in vitro respond very differently to chromium and nickel.

Hidradenitis Suppurativa and Zinc: A New Therapeutic Approach

BACKGROUND

Hidradenitis suppurativa (Verneuil's disease) is a chronic suppurative dermatosis involving apocrine glands with a severe impact on the quality of life, which is enhanced by the fact that the drugs usually prescribed are poorly effective.

OBJECTIVE

We discuss a new therapeutic approach based on zinc salts.

METHODS

We performed a pilot study on 22 patients, mainly from grade I or II in Hurley's classification. All included patients had previously been prescribed a treatment (antibiotic, isotretinoin, surgery or anti-androgens), which was inefficient. They were then treated with 90 mg of zinc gluconate per day (15 mg zinc per Rubozinc capsule).

RESULTS

We observed a clinical response in all patients, with 8 complete remissions (CR) and 14 partial remissions (PR). When CR was obtained, the treatment was progressively decreased (average of 3.5 capsules/day); 4/22 patients experienced side-effects, mainly gastro-intestinal.

CONCLUSION

Zinc salts could provide a new therapeutic alternative for the treatment of hidradenitis suppurativa.

Évaluation du potentiel photosensibilisant du gluconate de zinc

INTRODUCTION

Tolerance and clinical efficacy of zinc gluconate are well documented, however, no study have evaluated its photosensitizing potential. It is well known that many treatments of acne are photosensitizing. Evaluation of the photosensitizing potential of zinc gluconate was the aim of this study.

PATIENTS AND METHOD

Two open, monocentric studies were carried out with acneic volunteers. The methodology used in this study was an adaptation from that existing for the evaluation of the photosensitizing potential of topical products. In the study of phototoxic potential, volunteers were exposed to 20 J/cm2 UVA and to 0.75 times MED, before and after administration of zinc gluconate. Clinical and colorimetric evaluations of reactions were then carried out 1, 24, 48 and 72 hrs after exposure. In the photoallergic potential study, during the first week of the induction phase, the volunteers were exposed to 2 times MED, and to 3 times the MED during the second and third week. Then during the challenge phase, they were exposed t o4 J/cm2 UVA and to 0.75 times MED. Zinc gluconate was administered throughout the study. Clinical and colorimetric evaluations of reactions were carried out 24, 48 and 72 hrs after exposure, only during the challenge phase.

RESULTS

The majority of clinical scores measured on scales at 6 and 5 levels were equal to 0 and 0.5 (evaluation of the phototoxic potential) or all equal to 0 (evaluation of the photoallergic potential). Thus zinc gluconate did not induce phototoxic or photosensitive reactions, whatever the ultraviolet type used.

DISCUSSION

Since zinc gluconate does not induce any photosensitive reaction, it could be prescribed during periods of exposure to sun.

Efficacy of Boric-Complexed Zinc and Acetic-Complexed Zinc Otic Preparations for Canine Yeast Otitis Externa

The purpose of this 2-week, double-blinded, controlled clinical trial was to evaluate the efficacy of topical amino acid-complexed zinc gluconate formulated with boric acid (ZGB) or acetic acid (ZGA) versus a topical placebo in the treatment of yeast otitis externa in dogs. Included in the study were dogs with otitis externa and a cytopathological finding of yeast organisms in the affected ear. Ears were treated with the placebo, ZGA, or ZGB medications. Yeast counts as well as clinical appearance of the ears were monitored. Results revealed that ZGB significantly reduced the number of yeast organisms in cases of otitis externa.

Sels de zinc en dermatologie

Zinc is an essential trace element for the human organism. It acts like cofactor for the metalloenzymes involved in many cellular processes. Its anti-inflammatory activity, which is the basis of therapeutic use, other than acrodermatitis enteropathica, is not well known: production of cytokines, antioxidant activity. Its toxicity is very low, but marked at high doses during chronic administration by the risk of hypocupremia. It is not teratogenic and can be given during pregnancy. Its absorption, through the duodenum, is inhibited by excessive phytate intake. Maximum concentration is reached after 2 to 3 hours. It is widely distributed in the organism, mainly in muscles and bone. Excretion is predominantly digestive. Its spectacular effect in acrodermatitis enteropathica, through compensation of genetically determined malabsorption was discovered in 1973. Its usefulness in acne is based on the anti-inflammatory action and was first described with zinc sulfate, then with better tolerated gluconate. Many controlled studies have shown an efficacy on inflammatory lesions. Doses varied from 30 to 150 mg of elemental zinc and studies against cyclines have shown that minocycline has a superior effect; but zinc might be an alternative treatment when cyclines are contraindicated. To date we don't have convincing data for its use in other indications (leishmaniosis, warts, cutaneous ulcers). Tolerance at usual doses (200 mg of zinc gluconate or 30 mg of elemental zinc) is good. Major side effects are abdominal with nausea, vomiting, but are fleeting and dose dependent.

Ni2+ enhances Fe2+/peroxide-induced oxidation of arachidonic acid and formation of geno/cytotoxic 4-hydroxynonenal: a possible contributory mechanism in nickel toxicity and allergenicity

Ni(2+), a toxic, carcinogenic and allergenic agent, affected both the kinetic and chemical courses of the Fe(2+)-induced oxidation of arachidonic acid (AA) in 0.05 M phosphate buffer (pH 7.4) and at 37 degrees C. At 10 microM concentration, Ni(2+) decreased the rate of oxidation of peroxide-free AA (200 microM) promoted by 50 microM Fe(2+), as determined by measurement of thiobarbituric acid reactive species (TBARS) and 1H NMR analysis. However, in the presence of low levels of peroxides (e.g. 2%), Ni(2+) exerted a significant stimulatory effect on Fe(2+)-induced AA oxidation and TBARS formation. 1H NMR analysis showed that Ni(2+) (10 microM) enhanced formation of genotoxic alkenals including 4-hydroxy-2-nonenal (4-HNE, GC/MS evidence) by Fe(2+)-promoted degradation of both AA and 15-hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE) methyl esters. The observed stimulatory effects of Ni(2+) on peroxide breakdown and cytotoxic aldehyde formation provide an attractive explanation to the enhanced sensitization capacity of nickel in inflammatory states compared to normal states.

Multicenter randomized comparative double-blind controlled clinical trial of the safety and efficacy of zinc gluconate versus minocycline hydrochloride in the treatment of inflammatory acne vulgaris

BACKGROUND

In addition to tetracyclines, zinc may constitute an alternative treatment in inflammatory lesions of acne.

OBJECTIVE

To evaluate the place of zinc gluconate in relation to antibiotics in the treatment of acne vulgaris.

METHODS

Zinc was compared to minocycline in a multicenter randomized double-blind trial. 332 patients received either 30 mg elemental zinc or 100 mg minocycline over 3 months. The primary endpoint was defined as the percentage of the clinical success rate on day 90 (i.e. more than 2/3 decrease in inflammatory lesions, i.e. papules and pustules).

RESULTS

This clinical success rate was 31.2% for zinc and 63.4% for minocycline. Minocycline nevertheless showed a 9% superiority in action at 1 month and one of 17% at 3 months, with respect to the mean change in lesion count. Regarding safety, the majority of the adverse effects of zinc gluconate and of minocycline concerned the gastrointestinal system and were moderate (5 dropouts with zinc gluconate and 4 with minocycline).

CONCLUSION

Minocycline and zinc gluconate are both effective in the treatment of inflammatory acne, but minocycline has a superior effect evaluated to be 17% in our study.

Nickel-induced proteins in human HaCaT keratinocytes: annexin II and phosphoglycerate kinase

It has been established in previous in vitro experiments with human HaCaT keratinocytes that nickel becomes cytotoxic at concentrations higher than 100 microM and that it is accumulated mainly in the cytosolic fraction (Ermolli et al., 2000). The aim of this work was to search possible biomarkers of metal insult, i.e. nickel-binding proteins or proteins differentially expressed in the cytosolic fraction of nickel-exposed cells (up to 1 mM nickel) as compared to controls. Cytosolic proteins were studied by isoelectric focusing (IEF) and two-dimensional gel electrophoresis (2-DE). Separation by IEF revealed nickel-induced changes in the abundance of cytosolic proteins as visualised with nickel-nitrilo-triacetic-alkaline phosphatase (Ni-NTA-AP) in blots. The cytosolic fraction of cells incubated with nickel, at concentrations over 100 microM, showed nickel binding components which were absent or present in significantly lower amounts in control cells. These proteins had isoelectric points (pIs) 6.9, 7.7 and 8.5. After 2-DE silver- and protein staining significantly increased abundance of four proteins was observed. Their pI values corresponded to those of the nickel binding ones seen after IEF. A protein with pI 6.9 had a molecular weight estimated to 38 kDa, two proteins with pI around 7.7 showed molecular weights of 57 and 22 kDa, respectively and another protein with pI of 8.5 had a molecular weight of 33 kDa. The increased abundance of these components, both in IEF experiments and in 2-DE, correlated with the nickel concentration in the culture media. N-terminal amino acid sequencing and database search allowed identification of one a protein as phosphoglycerate kinase and another one as annexin II. The involvement of these proteins in cellular functions and their possible implications in the mechanism of nickel toxicity in keratinocytes are discussed. Some of these proteins may be biomarker candidates for effects of nickel exposure in human keratinocytes.